1. Field of the Invention
The present invention relates to a space potential generator that discharges a static electricity to a space to form an electric field, a freshness-keeping device to keep freshness of food or the like using the space potential generator, and a fryer provided with the space potential generator.
2. Description of Related Art
Conventionally, preserving food in an electric field is proposed to suppress bacteria growth and prevent deterioration of the food (Patent documents 1 to 3).
The invention described in the patent document 1 aims for performing an electric field processing evenly to objects. An inner electrode and an outer electrode, which is arranged around the inner electrode, are provided. An electric field processing area is formed between the inner electrode and the outer electrode. By applying an AC voltage having the same polarity to each of the electrodes, a positive electric field and a negative electric field are alternately generated on the electric field processing area.
In the invention described in the patent document 2, a conductive electrode is provided in a refrigerator as a shelf board, and the conductive electrode is connected to a high voltage generator provided outside the refrigerator. Thus, an electrostatic field is generated around the conductive electrode, which is provided as the shelf board.
In the invention described in the patent document 3, a pair of electrodes is provided in a storage compartment, and an electric field is formed in the storage compartment by applying a voltage to the pair of electrodes.
[Patent Document 1] International Publication No. WO2006/054348
[Patent Document 2] Japanese patent No. 4445594
[Patent Document 3] Japanese Unexamined Patent Application Publication No. 2012-207900.
In the inventions described in the patent documents 1 to 3, the electric field is formed and food is preserved in the electric field. Thus, bacteria growth is suppressed and deterioration of the food is prevented.
However, in the inventions described in the patent documents 1 to 3, the electric field is formed between the electrodes and the food is preserved in the electric field formed between the electrodes. Therefore, two or more outputs are necessarily required and a structure becomes complicated. Furthermore, a size of the space to store the food is limited because a distance between the electrodes is limited.
In the invention described in the patent document 2, judging from its circuit configuration, the electric field can be formed only immediately near the conductive electrode, which is provided as the shelf board. Therefore, unless the food is in contact with the shelf board, an effect of the electric field cannot be obtained.
In particular, in the inventions described in the patent documents 2 and 3, judging from their configurations, the effect can be obtained only when an electrode shelf board is provided entirely in the refrigerator. Therefore, the shelf board having a dimension corresponding to the size of the refrigerator should be preliminarily produced and the produced shelf board should be installed on the refrigerator by a welding work or the like. When post-installing the space potential generator in a refrigerating compartment or the like, cost and time are needed and a large amount of facility investment is required. In addition, since the electrode shelf board should be installed in the refrigerator, a capacity of the refrigerator is reduced by the electrode shelf board.
Also in the invention described in the patent document 1, the electric field is formed only at a space between two or more electrodes. Therefore, a plurality of electrodes having a dimension corresponding to the size of the refrigerator should be preliminarily produced and the produced electrodes should be installed to cover whole the refrigerator. Thus, a location to install the electrodes is limited. It is difficult to post-install the electrodes in an existing refrigerator or the like.
In the invention described in the patent documents 1 to 3, current intensity is high. Therefore, an electromagnetic shield should be installed in entire the refrigerator.
Furthermore, in a case of a large-size prefabricated refrigerator or a large-scale storehouse, a voltage of 5000 to 10000 V is required to supply electricity to a large-sized electrode shelf board or electrodes. Thus, electricity bill is expensive. In addition, the food to be preserved is directly placed on the electrode shelf board to which the voltage of 5000 to 10000 V is applied. Therefore, electricity may be charged on a human body when a worker touches the food.
Furthermore, in the invention described in the patent documents 1 to 3, the electrode shelf board should be installed or a plurality of electrodes should be installed at a predetermined interval. Therefore, when installing them, the food in the refrigerator should be temporarily moved to another place.
Furthermore, in the invention described in the patent documents 1 to 3, an extremely large transformer having a large number of turns is required to obtain a necessary output voltage. Therefore, the device as a whole becomes large.
The present invention can solve the above described conventional problems. The present invention provides a space potential generator and a freshness-keeping device using the space potential generator enabling to downsize the device as a whole, keep a capacity of the refrigerator same as before the space potential generator is installed, and generate an electric field in a wide range.
In addition, the present invention provides a fryer that efficiently forms an electric field in an oil tub to prevent deterioration of oil and generation of acrylamide, shorten time required for frying, and reduce fat and oil smoke.